Hitherto, for connecting the circuits of electric and electronic instruments or devices of motor cars, connectors equipped with various kinds of plastic housings (hereinafter, sometimes referred to as simply "connectors") have been used. Recently, with the progress of the light-weight construction of a motor car together with the low air pollution by a motor car, the requirement for the light weight of connectors has been increased. Furthermore, with the increase of the performance and the function of a motor car, the connector has been required miniaturization, complication in its form, and improvement in heat resistance, fitting feeling and productivity thereof.
A PBT (polybutene terephthalate) resin excellent in heat resistance, dimensional stability and moldability has conventionally been used as a connector in large quantity, but since the PBT resin has a high specific gravity, there is a problem in that the weight of the connector made of the resin is increased. A 6-nylon resin and a 6,6-nylon resin are suitable for a light-weight connector since the specific gravity of these resins is lower than that of the PBT resin. However, these resins have problems in that they have a high water absorption to cause a dimensional change and deterioration of the mechanical properties by the absorption of water, and the connectors made of these resins are not suitable for miniaturized connectors, complication in its form, and improvement in fitting feeling.
In addition to the foregoing resins, a PP (polypropylene) resin, a PPE (polyphenyleneether) resin, an ABS (acrylonitrile-butadiene-styrene copolymer) resin, etc., have also been used, but these resins have problems in that they are inferior in heat resistance, chemical resistance, fluidity, etc., and hence these resins are not satisfactory.
Attempts to reduce the weight of connectors by foaming resins, or adding a hollow filler to resins have been investigated but in these attempts, there are problems in that the molding accuracy is insufficient, and the deterioration of the mechanical properties is severe.